1. Field of the Invention
This invention relates to the fabric belts used on papermaking machines to support, carry, and dewater a wet fibrous sheet as it is being processed into paper. More particularly, it relates to seamed, rather than woven endless, fabrics and to the installation of a pintle which joins the two ends of a pin-seamable fabric to one another to form an endless belt on a papermachine.
2. Description of the Prior Art
Endless fabric belts are key components of all three sections (forming, pressing, and drying) of the machines used to manufacture paper products. There, like a conveyor belt, they carry the wet fibrous sheet along as it is being processed into paper. At the same time, they provide needed support to the fragile wet paper sheet and dewater it by accepting water which drains or is pressed therefrom.
Generally, these fabrics are supplied either in endless form, that is, woven in the form of an endless loop without a seam, or in open-ended form. The latter must be closed into endless form when installed on the papermachine. This will require a seam running transversely across the fabric at the point where the two ends meet.
The so-called OMS (on-machine-seamed) fabrics are much easier to install on a papermachine position than those of the woven endless variety, and shall concern us here. To do so, one merely has to draw one end of the open-ended fabric through the machine and around the appropriate guide and tension rolls and other components. Then, the two ends can be joined at a convenient location on the machine and the tension adjusted to make the fabric taut. In practice, a new fabric is sometimes installed at the time an old one is being removed by connecting one end of the new fabric to the old fabric, which can then be used to pull the new fabric into proper position on the machine.
Alternatively, a rope, or ropes, can be attached to one end of the old fabric being replaced. When the other end of the old fabric is pulled out to remove it from the machine, the rope is drawn about the path formerly occupied by the fabric. This approach enables plant personnel to clean machine components before the new fabric is installed. To complete the entire operation, one end of the rope is attached to the leader of the new fabric, while the other end is pulled to draw the fabric onto the machine position.
The closure of a commonly used variety of seam will be our primary concern here. This type of seam is referred to as a pin seam. By design, it is more difficult to distinguish from the rest of the body of the fabric than those formed in other ways. The seam region on a fabric closed in this manner more closely resembles the rest of the body of the fabric, in terms of such parameters as permeability, than the corresponding regions in fabrics seamed in other ways.
A pin seam can be quite difficult to close. To do so, a thin cable, better known as a pintle, is passed through the tubular passage formed when the loops at each end of the fabric are alternated an intermeshed when the two ends are brought and held together. These loops are formed by the machine direction yarns of the fabric.
Typically, the pintle will be attache to a wire leader, which, because of its stiffness relative to that of the pintle, will be directed first through the tubular passage, then used to pull the pintle therethrough in needle-and-thread fashion.
The pintle may take the form of an extruded monofilament having a length at least as great as the width of the fabric whose ends are to be joined. Alternatively, the pintle may take any of the other forms commonly taken by the yarns used in the weaving of paper-machine clothing; that is to say, pintles may take the forms of plied or braided monofilament yarns, multi-filament or spun yarns, and so forth.
The present invention is designed to facilitate the task of installing a pintle by reducing the occurrence of tangles in the wire leaders and pintles during the closing of a pin seam on a papermachine fabric, so that this operation may be completed without undue loss of time.